Accuracy of comparison decisions by forensic firearms examiners

Journal of Forensic Sciences, Journal Year: 2022, Volume and Issue: 68(1), P. 86 - 100

Published: Oct. 1, 2022

Abstract This black box study assessed the performance of forensic firearms examiners in United States. It involved three different types and 173 volunteers who performed a total 8640 comparisons both bullets cartridge cases. The overall false‐positive error rate was estimated as 0.656% 0.933% for cases, respectively, while false negatives 2.87% 1.87% respectively. majority errors were made by limited number examiners. Because chi‐square tests independence strongly suggest that probabilities are not same each examiner, these maximum‐likelihood estimates based on beta‐binomial probability model do depend an assumption equal examiner‐specific rates. Corresponding 95% confidence intervals (0.305%, 1.42%) (0.548%, 1.57%) positives (1.89%, 4.26%) (1.16%, 2.99%) results this consistent with prior studies, despite its comprehensive design challenging specimens.

Language: Английский

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The false promise of firearms examination validation studies: Lay controls, simplistic comparisons, and the failure to soundly measure misidentification rates

Journal of Forensic Sciences, Journal Year: 2024, Volume and Issue: 69(4), P. 1334 - 1349

Published: April 29, 2024

Abstract Several studies have recently attempted to estimate practitioner accuracy when comparing fired ammunition. But whether this research has included sufficiently challenging comparisons dependent upon expertise for accurate conclusions regarding source remains largely unexplored in the literature. Control groups of lay people comprise one means vetting question, assessing comparison samples were at least enough distinguish between experts and novices. This article therefore utilizes such a group, specifically 82 attorneys, as post hoc control juxtaposes their performance on set cartridge case images from commonly cited study (Duez et al. J Forensic Sci. 2018;63:1069–1084) with that original participant pool professionals. Despite lacking kind formalized training experience common latter, our participants displayed an ability, generally, cases by same versus different guns 327 they performed. And while rates lagged substantially behind those professionals same‐source comparisons, different‐source was essentially indistinguishable trained examiners. indicates although we vetted may provide useful information about professional performing it little offer terms measuring examiners' ability guns. If similar issues pervade other studies, then there is reason rely false‐positive generated.

Language: Английский

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Treatment of inconclusives in the AFTE range of conclusions

Law Probability and Risk, Journal Year: 2020, Volume and Issue: 19(3-4), P. 317 - 364

Published: Dec. 1, 2020

Abstract In the past decade, and in response to recommendations set forth by National Research Council Committee on Identifying Needs of Forensic Sciences Community (2009), scientists have conducted several black-box studies that attempt estimate error rates firearm examiners. Most these resulted vanishingly small rates, at least one them (D. P. Baldwin, S. J. Bajic, M. Morris, D. Zamzow. A Study False-Positive False-Negative Error Rates Cartridge Case Comparisons. Technical report, Ames Lab IA, Performing, Fort Belvoir, VA, April 2014.) was cited President’s Advisors Science Technology (PCAST) during Obama administration, as an example a well-designed experiment. What has received little attention, however, is actual calculation particular, effect inconclusive findings those estimates. The treatment inconclusives assessment errors far-reaching implications legal system. Here, we revisit area firearms examination, investigating their results. It clear there are stark differences rate results regions with different norms for training reporting conclusions. More surprisingly, decisions materials from sources notably higher than same-source some regions. To mitigate effects this difference propose unifying approach directly applicable forensic laboratories settings.

Language: Английский

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Evaluating firearm examiner conclusion variability using cartridge case reproductions

Journal of Forensic Sciences, Journal Year: 2021, Volume and Issue: 66(5), P. 1704 - 1720

Published: May 31, 2021

Abstract The forensic science pattern comparison areas, including fingerprints, footwear, and firearms, have been criticized for their subjective nature. While much research has attempted to move these disciplines more objective methods, examiners are still coming conclusions based on own training experience. To complement this subjectivity, black box studies necessary establish the accuracy of feature‐comparison methods. However, when cartridges fired by a firearm create cartridge case test sets there may be significant variability within resulting impressions. This can result in different participants receiving with varying levels difficulty differences impression quality. Therefore, between is not straightforward. compare examiners, method called double‐casting was used plastic reproductions. Double‐casts twenty‐one master cases were created mailed examiners. double‐casts ensured that all comparing exhibits same level detail. tasked determining if unknown each set as three knowns. Automated comparisons also set. results from study showed examiner examining evidence. Furthermore, it shown automated metrics would benefit quality control measure correct any potential errors strengthen conclusions.

Language: Английский

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Results of the 3D Virtual Comparison Microscopy Error Rate (VCMER) Study for firearm forensics

Journal of Forensic Sciences, Journal Year: 2020, Volume and Issue: 66(2), P. 557 - 570

Published: Oct. 26, 2020

Abstract The digital examination of scanned or measured 3D surface topography is referred to as Virtual Comparison Microscopy (VCM). Within the discipline firearm and toolmark examination, VCM enables review comparison microscopic toolmarks on fired ammunition components. In coming years, this technique may supplement potentially replace light microscope primary instrument used for examination. This paper describes a error rate validation study involving 107 participants. included 40 test sets cartridge cases from firearms with variety makes, models, calibers. Participants commercially available software which allowed data distribution, specimen visualization, submission conclusions. also participants annotate areas similarity dissimilarity support their cohort 76 qualified United States Canadian examiners that completed had an overall false‐positive 3 errors 693 comparisons (0.43%) false‐negative 0 491 (0.0%). accuracy supplemented by participant's provided annotations provide insight into cause consistency across independent examinations conducted in study. ability obtain highly accurate conclusions fires wide range supports hypothesis useful tool within crime laboratory.

Language: Английский

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Interpol review of shoe and tool marks 2016-2019

Forensic Science International Synergy, Journal Year: 2020, Volume and Issue: 2, P. 521 - 539

Published: Jan. 1, 2020

This review paper covers the forensic-relevant literature in shoe and tool mark examination from 2016 to 2019 as a part of 19th Interpol International Forensic Science Managers Symposium. The papers are also available at website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Language: Английский

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Combined interpretation of objective firearm evidence comparison algorithms using Bayesian networks

Journal of Forensic Sciences, Journal Year: 2024, Volume and Issue: 69(6), P. 2028 - 2040

Published: Aug. 22, 2024

Abstract Traditionally, firearm and toolmark examiners manually evaluate the similarity of features on two bullets using comparison microscopy. Advances in microscopy have made it possible to collect 3D topographic data, several automated algorithms been introduced for bullet striae these data. In this study, open‐source approaches cross‐correlation, congruent matching profile segments, consecutive striations, a random forest model were evaluated. A statistical characterization was performed four datasets consecutively manufactured firearms provide challenging scenario. Each approach applied all samples pairwise fashion, classification performance compared. Based findings, Bayesian network empirically learned constructed leverage strengths each individual approach, relationship between results, combine them into posterior probability given comparison. The evaluated similarly approaches, results developed classified 99.6% correctly, resultant distributions significantly separated more so than when used isolation.

Language: Английский

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Quantitative matching of forensic evidence fragments using fracture surface topography and statistical learning

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: Sept. 8, 2024

Language: Английский

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Quantitative matching of forensic evidence fragments utilizing 3D microscopy analysis of fracture surface replicas

Journal of Forensic Sciences, Journal Year: 2022, Volume and Issue: 67(3), P. 899 - 910

Published: March 7, 2022

Abstract Silicone casts are widely used by practitioners in the comparative analysis of forensic items. Fractured surfaces carry unique details that can provide accurate quantitative comparisons fragments. In this study, a statistical comparison protocol was applied to set 3D topological images fractured surface pairs and their replicas confidence between items silicone cast replicas. A 10 stainless steel samples were from same metal rod under controlled conditions replicated using standard casting technique. Six maps with 50% overlap acquired for each pair. Spectral analyses utilized identify correlation features at different length scales topology. We selected two frequency bands over critical wavelength (greater than two‐grain diameters) comparison. Our model matrix‐variate t ‐distribution accounts match non‐match population densities. decision rule identified probability matched unmatched surfaces. The proposed methodology correctly classified posterior exceeding 99.96%. Moreover, replication technique shows potential accurately replicating fracture greater 20 μm, which far exceeds feature range on most metallic alloy framework establishes basis limits articles while providing reliable mechanics‐based

Language: Английский

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Authors' response

Journal of Forensic Sciences, Journal Year: 2024, Volume and Issue: 69(6), P. 2346 - 2348

Published: Aug. 26, 2024

We read Mr. Marshall's commentary with interest, but unfortunately his submission—riddled ad hominem attacks on the motivations of firearms examination's critics and just shy reference-less—nigh-uniformly concentrates, not our study design or data, bemoaning notion that examiners' grandiose claims near infallibility (e.g., "practical impossibility" error [1]) should rest empirical grounds rather than tradition intention. In this way, Marshall has built a soapbox in lieu scientific critique, one, despite warnings old parable, raised up sand stone. Indeed, preference for weaving self-serving narrative victimization over engaging substantively findings evinces itself even when considering attention to detail he must have employed reading article. How else, through cursory review could criticize us treating Duez et al. [2] as an "error rate study"—rather simply "validation technique virtual comparison microscopy"—given repeated explicit discussion ways which FBI, DOJ, one study's authors promoted it proof low false-positive field examination [3-6]? Had thoroughly evaluated treatment control groups—including its reference, long storied history controls [7], also studies utilized novices contextualize performance forensic professionals [3, 8, 9]—would he, really characterize suggestion validation include such groups "new unusual"? And why else would felt necessary point out limitations (the use attorneys group lay people photos opposed 3D scans cartridge cases) we had already forthrightly acknowledged original article [3]? gone further—for example, managed muster any argument supported by references data might erred suggesting actually disadvantaged participants—he found ready willing engage robust back forth, if reconsider conclusions. That did leaves little respond to. But because cannot, at juncture, ask go try again, few points warrant brief discussion. A condition is something happen happen. Being human going college, colleges do admit other animals. sufficient that, present, bound happen; so being all beings college. contrast, dropping lighted match into bucket gasoline starting fire, condition, there are many rubbing two sticks together. Notice empty be neither nor fire; usually conditions concur act specific causal consequences. [11] Along similar lines, makes sense article's focus (much less accuse malicious intent) merely ability separate professional novice does alone suffice render capable definitively proving validity. Just value no set ever (in isolation) resolve debate, suitable research they answer question interest. Physicians, after all, ignored HIV necessary, sufficient, developing more serious AIDS [14]. Viewed light, characterization some sinisterly plotted "gotcha" moment shows true colors knee-jerk reaction well-reasoned critique. Second, solitary foray rebutting conclusions own—his recent paper Growns [15]—relies gross mischaracterizations aims limitations. short, portrays establishing likely outperform comparing fired bullets cases. paper, tested only visual abilities included single within participant pool, done nothing sort. specifically reject very inference draws from their findings, noting "[a]s participants were untrained novices, unclear whether these results generalize practicing professionals" [15]. Really though, grateful directing al.'s excellent because, reality, supports made article, citing showing domain expertise fields acknowledging none exist realm examination, emphasizing larger-than-expected role "domain-general ability" "varies naturally general population" emerging training experience (a finding logically impel further dispense need compare performance) words, while remain perplexed belief citation served ends—especially inconsistency between view validity settled statement "research beginning explore comparison" [15]—we thank him including how adequately establish accuracy practitioners Third, fares better mounting defense own effort validate microscopy [16]. He quoted saying "[t]here was intention select pairs elimination sets attempt lead making false positive source attribution," parenthetical followed: "(e.g. strong carry subclass characteristics pairs)," doing failed recognize way latter "changes meaning" quotation, difficulty coauthors indeed, Marshall—now originally wrote them, cannot say—who misunderstands words. The highlights uses e.g. (meaning example many) i.e. is). Thus, portraying Knowles efforts whatsoever inject sets, misunderstood misrepresent paper. now fault assume grammatical usage errors part coauthors. More point, however, used said parenthetical, concerns about bias against testing challenging eliminations stand. provides support anecdotal conjecture rarity characteristics, justify ignoring evaluation practitioner grappling marks, especially produced staggering rates misidentification test examiners [12]. troublingly still, calls assertions nonexistent challenge "categorically misleading," evidence cites applied exclusively identifications. repeatedly dismisses inconsequential, different (just 20% total study) "were significant final outcome research" listing first (and thus logically, primary) rationale "to reduce potential identification response bias" Given harms criminal defendants based individual [17, 18], laboratory's policies can excuse shortcomings satisfy who demanded misidentification. Having dispensed substantive divine commentary, final, albeit philosophical, distinction draw views his. Early remarks, paradoxically accuses both remaining perpetually tethered record existed 2016 well to, opinion, "move goal posts" what adherents discipline demonstrate assuage doubts frankly understand former claim given himself concedes, expanded understanding appropriate harkening PCAST's criteria. assertion find disquieting. No scientist bemoan chance expand base knowledge develop new techniques technologies. most sickly stunted version method harbor precedent past. Down road dunkers women prove witchcraft, phrenologists measuring bumps skulls uphold racist hegemony, backwater physicians still bleeding those burdened illness; them enraged empiricism replace tradition. hold grander vision endeavor research, relish opportunity naysayers wrong proven themselves, life liberty impacted methods treasure bare minimum, ground beliefs desire. If hope see again solid literature under law, take expansive formidable view. They cease begrudging goalposts continue long, hard grind reflection research. make Marshalls world minority.

Language: Английский

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